Pan head screws have a broad head with rounded edges — the shape of an inverted frying pan. They are made in a variety of sizes and lengths and with various styles of threading. These types of screws are often used to secure machine parts, particularly when the components are made out of metal, but are used for many other applications such as woodworking. The slot on a pan head screw is typically a Phillips- or crosshead-slot, although other slot types are used as well. Pan heads screws are also made with unique or uncommon features. For instance, vented screws, that have that have a bored core through the center of the screw are used for machines that need to expel excess gas.
Many machines use pan head screws, including those found in industrial settings. For example, electro-hydraulic servo valves are used to control hydraulic fluids in an assortment of industrial machinery and are often constructed with pan head screws. These kinds of screws are also used to secure other devices that may be made out of metal, such as guard rails or steel framing for walls. Pan head screws are also frequently used in vehicles, especially to attach exterior components such as headlights or license plates.
A variety of types of threading are available for pan head screws, depending upon the intended use, but when used in machinery, they are typically not designed to be self-tapping, making it necessary for the holes to be pre-threaded. A multitude of sizes and lengths are available as well. For example, a 2-inch (about 5-cm) pan head screw might be used to hang a picture on a wall with a metal stud while a very short screw with a pan head might be found in a computer case, either to secure components or to keep the parts of the case itself together. Pan head screws are manufactured with a number of different coatings, such as black phosphate, to protect against corrosion, or zinc for galvanization.
Strength and weight ratings, correct size and threading, and proper replacement procedures should all be taken into account when using pan head screws, especially when working with machinery. Screws will generally have a load capacity that should be confirmed before using them for any project that involves any great deal of weight bearing. When replacing a screw of this type, the user should ensure that the size and threading are the same as the screw that was originally used.